I guess I must be odd because my 1996 2.0L Zetec Contour is quieter running a mix of 2 1/2 quarts of Havoline conventional and 2 quarts of Havoline synthetic, both 5W-20. Since new I've used 5W-30, 10W-30 and 5W-50 mainly synthetic oils. I did this mix because I had unwanted older oils left over and using them in an older vehicle that was back spec'd for 5W-20 anyway was ok. It's the quietest this vehicle has ever been. I don't drive the vehicle hard so I'm not worried about using modern 5W-20 oils.
Whimsey